c - 收到 Seg Fault 11 错误，但不知道原因

Question

我有一段代码，用于检查宏是否已定义，如果没有，则为新宏分配内存并将其添加到当前列表中。如果它已经定义了，那么它只是更改宏体，并保持名称不变。

static struct macro *macro_lookup(char *name){
  struct macro * temp = &macro_list;
  while(temp->next != NULL){
    if(strcmp(temp->macro_name,name) == 0){
      return temp;
    }
  }
  return NULL;
}

void macro_set(char *name, char *body){
  //Need to check to see if a macro is already set for the name if so just change the body
  struct macro * p = macro_lookup(name); //Will return NULL if macro is not in the list. This line gives me the error of segmentation fault 11, if I comment it out the program works.
  //Need to make a new macro and add it to the list
  if(p == NULL){ 
    //Make a new macro
    struct macro * new_macro = (struct macro *)  Malloc(sizeof(struct macro)); //Malloc is my version of malloc, it works just fine.
    if(new_macro == NULL){
      fprintf(stderr,"Error while allocating space for the new marco.\n");
      exit(EXIT_FAILURE);
    }
    new_macro->macro_name = name;
    new_macro->macro_body = body;
    //Create a pointer to the list and traverse it until the end and put the new macro there
    struct macro * temp = &macro_list;
    while(temp->next != NULL){
      temp = temp->next;
    }
    temp->next = new_macro;
  }
  //The macro already exists and p is pointing to it
  else{
    //Just change the body of the macro
    p->macro_body = body;
  }
}

我不知道为什么上面的错误行给我带来了问题，我可以静态地将 p 设置为 null 并测试它，它工作正常，但是当我使用 Macro_lookup 函数时，它会出现段错误。

Answer 1

在macro_lookup()中，您检查temp->next不是NULL，但是temp又如何呢？是NULL？另外，temp->macro_name 为 NULL 又如何呢？或者未初始化？或者 name 为 NULL 或未初始化？当出现段错误时，调试器会向您显示什么？另外，您没有增加 temp (这很糟糕，因为您的循环永远不会结束)。